Share Repurchase Program (Schedule Of Shares Repurchased) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Proceeds from (Repurchase of) Equity [Abstract]
Shares repurchased	927	2,188
Average price per share	$ 347.09	$ 251.08
Total investment	$ 321,846	$ 549,428

Number of shares that have been repurchased and retired during the period.

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Name:	us-gaap_StockRepurchasedAndRetiredDuringPeriodShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration